https://leetcode.cn/problems/map-of-highest-peak/

class Solution {
    int dx[4] = { 0,0,-1,1 };
    int dy[4] = { -1,1,0,0 };
public:
    vector<vector<int>> highestPeak(vector<vector<int>>& isWater) {
        int m = isWater.size(), n = isWater[0].size();
        vector<vector<int>> dist(m, vector<int>(n, -1));

        queue<pair<int, int>> q;

        for (int i = 0; i < m; i++)
        {
            for (int j = 0; j < n; j++)
            {
                if (isWater[i][j])
                {
                    dist[i][j] = 0;
                    q.push({ i,j });
                }
            }
        }

        while (q.size())
        {
            auto [a, b] = q.front();
            q.pop();

            for (int i = 0; i < 4; i++)
            {
                int x = a + dx[i];
                int y = b + dy[i];

                if (x >= 0 && x < m && y >= 0 && y < n && dist[x][y] == -1)
                {
                    q.push({ x,y });
                    dist[x][y] = dist[a][b] + 1;
                }
            }
        }

        return dist;

    }
};